Option 1 contains some mistakes: You mix up "id" and "class". In the html you define an id but in the CSS you use a class. And the syntax for "backgound-image" is wrong. It must be "background-image: url(/download/attachments/4948755/header_softwear_100.jpg);"

Option 2, 3 and 4 won't work at all because the "Look and Feel > PDF Space Export > Header/Footer" only works for space exports (Browse > Advanced > PDF export). But what you are using is a page export (Tools > Export to PDF).